[MAX30102.js] is a module to handle the MAX30102 pulse oximetry and heart-rate monitor biosensor.
This module returns the raw IR and red light values as an array, but it's then up to you to analyse the data to get a heart rate or oxygen value.
The MAX30102 is a 1.8v device so requires its own voltage regulator (unless you have a breakout board that contains one). However the I2C lines are still capable of 3.3v.
var i2c = new I2C();
i2c.setup({scl: ..., sda: ...});
var hrm = require("MAX30102").connect(i2c);
function getHRM() {
print("Starting HRM...");
hrm.init();
var cnt = 200;
var rawdata = new Uint8Array(cnt*6);
var dcnt = 0;
// we wait for the HRM readings to settle down to sensible values
print("Waiting for HRM... wait 5 seconds");
var i = setInterval(function() {
hrm.readFIFORaw();
});
setTimeout(function() {
print("Reading HRM... wait 10 seconds");
clearInterval(i);
hrm.readFIFORaw(); // throw away the first set of readings...
var i = setInterval(function() {
// Save the raw data into an array
d = hrm.readFIFORaw();
rawdata.set(d, dcnt*6);
dcnt += d.length/6;
// when full, stop the HRM and then decode the data
if (dcnt>=cnt) {
hrm.kill();
clearInterval(i);
drawHRM(rawdata);
}
}, 200);
}, 5000);
}
function drawHRM(rawdata) {
var cnt = rawdata.length/6;
var dred = new Uint32Array(cnt);
var dir = new Uint32Array(cnt);
hrm.decodeRawData(rawdata, dred, dir);
var g = Graphics.createArrayBuffer(cnt,60,1);
var red = E.sum(dred)/cnt;
var ir = E.sum(dir)/cnt;
g.clear();
g.drawString("Red",2,2);
g.moveTo(-100,0);
for (var i=0;i<cnt;i++)
g.lineTo(i,30+(dred[i]-red)/20);
g.dump();
g.clear();
g.drawString("IR",2,2);
g.moveTo(-100,0);
for (var i=0;i<cnt;i++)
g.lineTo(i,30+(dir[i]-ir)/40);
g.dump();
}
getHRM();
// Start the heart rate monitor
MAX30102.prototype.init = function () { ... }
// Stop the heart rate monitor
MAX30102.prototype.kill = function () { ... }
// read one set of FIFO data, return {red,ir}
MAX30102.prototype.readFIFO = function () { ... }
// Read all the currently available FIFO data and return it raw
MAX30102.prototype.readFIFORaw = function () { ... }
// Decode an array of raw FIFO data into red&ir arrays (Uint32Array is preferable)
MAX30102.prototype.decodeRawData = function (d, red, ir) { ... }
exports.connect = function (i2c, options) { ... }
(No tutorials are available yet)
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